How do i solve? what are the steps?

1.) On A triangle you're trying to find "x" so what you do first is write the ratio from triangle A to triangle B.
3x + 11 / 42 (<-- fraction)     You see  the scale factor from A to B = 5:6
If you divide 5/6 it will equal to 0.833. So with the first fraction you try to equal it to the same with 5/6. I messed with the number and ended up getting 3(8)+11. if you multiply and add you will get 35. So then you get 35/42=0.833

3(x)+11/42=?
5/6=0.833

3(8)+11=35 --->  35/42 ---> =0.833 same as 5:6

2.) So this time we go from big to small.
40/16=2.5
45/2x+4=?

2(x)+4 ---> mess with sum #'s ---> 2(7)+4 = 18 ---> 45/18= 2.5