a.(x + 125) : 312 = 14 (dư 300)
x+125 = 14 x 312 + 300
x+125 = 4 668
x= 4 668 - 125
x=4 543
b.(x-234):23=128 (dư 21)
x-234=128 x 23 + 21
x-234=2 965
x=2 965 + 234
x=3 199
c.(x-24) x 2020=2020x33
(x-24)x2020=66 660
x-24=66 660:2020
x-24=33
x=33+24
x=57
d.5 x (x+2019)=3800 x 5
5 x (x+2019)=19 000
x+2019=19000:5
x+2019=3800
x=3800-2019
x=1 781
HẾT=)))