To solve these equations, we need to isolate the variable x. Let's solve each equation step by step:

a) x + 5.28 = 9.19

Subtract 5.28 from both sides:
x = 9.19 - 5.28

Simplifying the right side:
x = 3.91

b) x + 37.66 = 80.94

Subtract 37.66 from both sides:
x = 80.94 - 37.66

Simplifying the right side:
x = 43.28

c) x - 34.87 = 58.21

Add 34.87 to both sides:
x = 58.21 + 34.87

Simplifying the right side:
x = 93.08

So the solutions to the equations are:
a) x = 3.91
b) x = 43.28
c) x = 93.08