a) 2 1/4=(4*2+1)/4=9/4
a b/c=(c*a+b)/c
if you apply this formula ⇒ 4 1/3=13/3, 7 4/5=39/5, 2 3/5= 13/5
(9/4*x+13/3*x- 39/5): 13/5=
[x*(9*15/60 +20*13/60) - 39*12/60 ]*5/13=
[x(135+260)/60 - 468/60]*5/13=(395x-468)/60* 5/13=(395x-468)/156
b) I do not understand...please replay with the exercise