multiply first example by 3 and subtract by second example, you will get the following:
3*(5x + 2y) = 3*22 => 3*5x + 3*2y = 66 => 15x + 6y = 66
now subtraction:
(15x + 6y) - (-2x + 6y) = 66 - 3
15x + 6y + 2x - 6y = 63
15x + 2x + 6y - 6y = 63
17x = 63
x = 63/17 ≈ 3.705..... and as it says to round to the nearest tenth our answer would be: x = 3.7