## anonymous one year ago plz i need help :( Evaluate the expression if a = 1 and b = 2. fraction numerator 5 left parenthesis a star times plus 3 b right parenthesis over denominator a b end fraction A. 20 B. 5.5 C. 15 D. 17.5

1. freckles

$\frac{5( \star \cdot 3b)}{ab}$ any idea what the value we should plug in for the star ?

2. anonymous

1

3. freckles

so you are given $a=1, b=2, \star=1$

4. freckles

replace a with 1 replace b with 2 replace star with 1 then $\frac{5( \star \cdot 3b)}{ab}=\frac{5(1 \cdot 3(2))}{1(2)}$

5. anonymous

no the star is a

6. freckles

7. anonymous

and a is 1

8. anonymous

9. freckles

I'm sorry kind of confused about times plus and what that means exactly

10. freckles

can you draw the problem or is it really worded like that?

11. anonymous

ok

12. anonymous

|dw:1441573677006:dw|

13. freckles

$\frac{5(a+3b)}{ab} \\ \\ \text{ okay so replace } a \text{ with 1} \text{ and } b \text{ with 2} \\ \frac{5(1+3 \cdot 2)}{1(2)}$

14. freckles

do you know how to do 5(1+3*2) and 1(2)?

15. anonymous

no

16. freckles

1(2)? come on you know this 2

17. freckles

1 times a is a

18. freckles

1 times 2 is 2

19. anonymous

ok

20. freckles

5(1+3*2) here we apply order of operations what is 3*2?

21. anonymous

6

22. freckles

ok so we have now 5(1+6)

23. freckles

1+6=?

24. anonymous

7

25. freckles

and then whatever you get for 1+6 multiply that result by 5 so you should end up with 5 times 7

26. freckles

which is..

27. anonymous

35

28. freckles

$\frac{5(a+3b)}{ab} \\ \\ \text{ okay so replace } a \text{ with 1} \text{ and } b \text{ with 2} \\ \frac{5(1+3 \cdot 2)}{1(2)} \\ =\frac{5(1+6)}{2}=\frac{5(7)}{2}=\frac{35}{2}$

29. freckles

and you are basically done just need to write as a decimal

30. freckles

since your choices are written that way

31. anonymous

but there's no 35/2

32. freckles

yes that is why I said to write as a decimal

33. anonymous

35.2

34. freckles

how did you get 35.2?

35. freckles

|dw:1441574329519:dw| 2 doesn't go into 3, 3 times... 2 goes into 3, 1 times

36. freckles

|dw:1441574353259:dw|

37. freckles

2 goes into 15 how many times?

38. anonymous

oh

39. anonymous

7

40. freckles

|dw:1441574417155:dw| and finally 2 goes into 10 how many times?

41. anonymous

5

42. freckles

right |dw:1441574443279:dw| $\frac{35}{2}=17.5$

43. anonymous

thx