1.
a)x=4
b)x=7/8 - 5/4
x=(7-10)/8
x=-3/8
c)70+170+780=x
x=1020
2.
a+b=80
a/b=3/5 =>a=3b/5
3b/5 + b = 80
3b+5b=400
8b=400 =>b=50 si a=30
3.
Problema e incompleta...
4.
7(4x+5y)=8(x+5y)
28x+35y=8x+40y
20x=5y =>x/y=1/4
5.
25% inseamna 25/100 sau 1/4
1/4 x 320 = 80
6.
p₁_________100%
x__________125%
x=125·p₁/100=5p₁/4 pretul dupa prima scumpire de 25%
5p₁/4_________100%
y____________110%
y=5p₁·110/400=11p₁/8
11p₁/8 = 400 =>p₁=291 lei
