Answer:
15. D
16. B
17. A
18. D
Explanation:
For 15 you know that there is 22 kids in this years class and it has 8 more kids than last year. We dont know last year amount so its X so X+8=22
For 16 you are solving for y. You want to get y by it self so you subtract 15 from both sides than its 3/12y = -15 so you multiply by the reciprocal which is 12/3 so you get y= -60
17 you wanna get x by itself so we combine like terms so subtract x from 3x to get 2x-8=4 than you add 8 to both sides and get 2x=12 divide by to and u get x=6
18 you do the same thing subtract 1.2 to get 2.5x=-4.8 than divide by 2.5 to get x= -1.92