a=20
Step-by-step explanation
Step 1
Let x represents the number of hats
a represents the cost of 1 hat
so, the cost of the hats is
Also
Let y represents the number of pullovers
let 30 as the cost of 1 pullover
so, the cost of the pullovers is
so, the total cost is
Step 2
If each pullover costs $10 more than a hat, in other words you have to add 10 to the cost of the hat to get the cost of the pullover
Hence, the cost of 1 hat ( a) is 20.
I hope this helps you