1)(1/3+1/2)×x=3,75
5/6x=3,75
x=375/100÷5/6
x=375/100×6/5
x=9/2=4,5
2)(3/5-0,25)×x=4,9
(0,6-0,25)×x=4,9
0,35x=4,9
x=4,9÷0,35
x=14
3)(7/8-0,2)×x=8,1
(0,875-0,2)×x=8,1
0,675x=8,1
x=8,1÷0,675
x=12
4)(4-2 3/7)×x=2 5/14
(3 7/7-2 3/7)×x=2 5/14
1 4/7x=2 5/14
x=33/14÷11/7
x=33/14×7/11
x=3/2=1,5