the correct question is
Given that sinx=3/5 where x is an acute angle, what is cosx and tanx?
we know that
since x is acute 0<x<π/2
then the trigonometric rations will be positive
sin ²x+cos²x=1------------> cos²x=1-sin²x-------> cos²x=1-(3/5)²----> 1-(9/25)
cos²x=16/25----------> cos x=4/5
the answer part A) is
cos x=4/5
tan x=sin x/cos x
so
tan x=(3/5)/(4/5)---------> tan x=3/4
the answer part B) is
tan x=3/4