Question

у:12+15=21
2320-х:4=1990
1960-200:х=1910

Answer 1

y : 12 + 15 = 21
y = (21 - 15)*12
y = 72

2320 - x : 4 = 1990
2320 - 1990 = x : 4
x = 330*4
x = 1320

1960 - 200 : x = 1910
1960 - 1910 = 200 : x
x = 200 : 50
x = 4

Answer 2

y:12+15=21
y:12=21-15
y:12=6
y=12•6
y=72
72:12+15=21
21=21
2320-x:4=1990
x:4=2320-1990
x:4=330
x=330•4
x=1320
2320-1320:4=1990
1990=1990
1960-200:x=1910
200:x=1960-1910
200:x=50
x=200:50
x=4
1960-200:4=1910
1910=1910