Q8

For such situations, angles in a parallelogram which are next to each other add up to 180.

So, 3y + 2y = 180
(just like 3 units + 2 units = 180)

5y = 180
(just like 5 units = 180)

y = 36
(just like 1 unit = 36)

Q9

Angles in a triangle add up to 180.

So,

x + (x + 10) + (2x - 50) = 180
(just like 1 unit + 1 unit + 10 + 2 units - 50 = 180)

x + x + 10 + 2x - 50 = 180

We collect like terms together, just like collecting units together.

4x + 10 - 50 = 180
(just like 4 units + 10 - 50 = 180)

4x - 40 = 180
(just like 4 units - 40 = 180)

4x = 220
(just like 4 units = 220)

x = 55
(just like 1 unit = 55)