How do i find the value of the unknown variable

6x + 2 + 40 = 90

Let x = the unknown

6x + 42 = 90

6x = 90 - 42

6x = 48

x = 48/6

x = 8

x=8

Step-by-step explanation:

We know that 40 + (6x+2)  +90 = 180   since the three angles form a straight line

40 + (6x+2)  +90 = 180

Combine like terms

132 + 6x = 180

Subtract 132 from each side

132-132 +6x= 180-132

6x = 48

Divide each side by 6

6x/6 = 48/6

x = 8

220

Step-by-step explanation:

720 divided by 20 is 36. there are 11 defective collars. 36 times 20 is 220