Answer: x = 29
========================================================
Work Shown:
A = 2x+3
B = x
angles A and B are complementary, so they add to 90 degrees
A+B = 90
(2x+3)+(x) = 90
2x+3+x = 90
2x+x+3 = 90
3x+3 = 90
3x+3-3 = 90-3
3x = 87
3x/3 = 87/3
x = 29
Extra info:
2x+3 = 2(29)+3 = 58+3 = 61
Note that 29 and 61 add to 29+61 = 90