x+78+x=198
=>2Xx=198-78
=>2Xx=120
=>x=120:2
=>x=60
x + 78 + x = 198
x.x = 198 - 78
2x = 120
x = 120 : 2
x = 60
x + 78 + x = 198
X x 2 + 78 = 198
X x 2 = 198 - 78
X x 2 = 120
x = 120 : 2
x = 60
x + 78 + x = 198
X x 2 + 78 = 198
X x 2 = 198 - 78
X x 2 = 120
x = 120 : 2
x = 60