Look at the picture.
Therefore we have the equation:
10y - 29 = 7y + 19 add 29 to both sides
10y = 7y + 48 subtract 7y from both sides
3y = 48 divide both sides by 3
y = 16
3x + 7 = 5x - 21 subtract 7 from both sides
3x = 5x = -28 subtract 5x from both sides
-2x = -28 divide both sides by (-2)
x = 14