What is the amplitude of y = (3sinx/2) + 4?

Any link of proof would be appreciated if you have one

Thank you

y = (3sinx/2) + 4

If you mean
y = 3 sin (x/2) + 4
the amplitude is 3
It goes up from 4 to 7 when the sine is +1 and down from 4 to 1 when the sine function is -1