1)13х+9х+13=321
2)(х-42)*13=390
3)(7х-х)÷5=180

1) 13х + 9х + 13 = 321
Combining like terms, we get:
22х + 13 = 321
Subtracting 13 from both sides, we get:
22х = 308
Dividing both sides by 22, we get:
х = 14

2) (х-42) * 13 = 390
Expanding the left side, we get:
13х - 546 = 390
Adding 546 to both sides, we get:
13х = 936
Dividing both sides by 13, we get:
х = 72

3) (7х - х) ÷ 5 = 180
Combining like terms, we get:
6х ÷ 5 = 180
Multiplying both sides by 5, we get:
6х = 900
Dividing both sides by 6, we get:
х = 150