3
Explanation:
1.3z + 1.5 = 5.4
Make z the subject in the equation by making it stand alone, by so doing, the transferred figures will have a change in sign i.e if it's a negative sign that's gonna be transferred it will change into a positive sign and vice versa.
The equation will this be; 1.3z = -1.5 + 5.4
1.3z = 3.9
Divide both sides by the co-efficient of the unknown figure. In other words, you'll divide both sides by the number beside the unknown letter.
z = 3.