The equation 3w + 4j = 39 is used to determine the number of water bottles w and the number of juice bottles j that can be bought for $39. If you purchase 6 bottles of juice, how many bottles of water can you buy? A. 3 B. 5 C. 15 D. 17

How I got this

j = 6 because you bought 6 bottles of juice

We use this to find the value of w

3w + 4j = 39

3w + 4(6) = 39 ... j replaced with 6 since j = 6

3w + 24 = 39

3w + 24-24 = 39-24 ... subtract 24 from both sides

3w = 15

3w/3 = 15/3 ... dividing both sides by 3

w = 5

If j = 6, then w = 5

To check this, we plug both values into the equation and we should get 39 on both sides

3w + 4j = 39

3(5) + 4(6) = 39

15 + 24 = 39

39 = 39 ... true statement; answer is confirmed

associative property of multiplication