Explanation:
13.
a/7 + 5/7 = 2/7
a/7 = 2/7 - 5/7 = -3/7
a = -3
14.
6v - 5/8 = 7/8
6v = 7/8 + 5/8 = 12/8
v = 12/8 / 6 = 2/8 = 1/4
15.
j/6 - 9 = 5/6
j - 54 = 5
j = 5 + 54 = 59
16.
0.52y + 2.5 = 5.1
0.52y = 5.1 - 2.5 = 2.6
y = 2.6/0.52 = 5
17.
4n + 0.24 = 15.76
4n = 15.76 - 0.24 = 15.52
n = 15.52/4 = 3.88
18.
2.45 - 3.1t = 21.05
-3.1t = 21.05 - 2.45 = 18.6
t = 18.6/-3.1 = -6