Question

( a x 20 ) x 0,4 - 13 = a x 0,75

Answer 1

( a x 20 ) x 0,4 - 13 = 0,75a
a x 20 x 0,4 -13= 0,75 a
8 a-0,75 a=13
7,25 a =13
a = 1,79

Answer 2

( a x 20 ) x 0,4 - 13 = a x 0,758a-13=0,75a
8a-0,75a=13
7,25a=13
a=13/7,25
a=13/1:725/100=1300/725=simplif cu 5=260/145=52/29
a=52/29