2tens and 15 ones write the number in words

Thirty five. is 10 + 10 + 15

Thirty-five
2 tens is 20 + 15 = 35

First, let x = number of oatmeal bars that Liam bakes

The expression should look like this:
(x + 20) + x = 108
Now, solve.
x + 20 + x = 108
2x + 20 = 108     Simplify the expression by making x + x = 2x.
     - 20      - 20   Subtract 20 to isolate x.

2x         = 88
---             ---   Divide them by two to isolate the variable x.
2               2

x           = 44    So, Liam baked 44 oatmeal bars.

Now, to find how many bars Hamsa baked, you have to do 44 + 20, because she baked 20 more than Liam. So, Hamsa baked 64 oatmeal cookies.

The ratio is now 64:44, which is 16:11 when simplified. 

Hope I helped!