7/4 = 3/a (Find the value of a )

T-5/4 = 3/2 (Find the value of T)

x/9 = 0.24/3 (Find the value of x )

These are proportions.

Cross multiply and solve for the unknown value.

7/4 = 3/a
7a = 12
a = 12/7 = 1 5/7