bonsoir
7/9y +5 = 8
7/9y = 8-5
7/9y = 3
y = 3*9/7
y = 27/7
1/16x -2 = 5/8
1/16x = 5/8+2
1/16x = 5/8+16/8
1/16x = 21/8
x = 21/8 * 16
x = 21x2
x =42
1/4x -3/8 = 2/3
1/4x = 2/3+3/8
1/4x = 16/24+9/24
1/4x = 25/24
x = 25/24 *4
x = 25/6
3/7y -5/35 = -8/14
3/7y = -8/14 +5/35
3/7y = -40/70 +10/70
3/7y = -30/70
3/7y = -3/7
y = -3/7 * 7/3
y = -1