Can someone please help me

Twice the sum of a number and 4 is equal to three times the difference of the number and 7. find the number.

Tell whether the two rates form a proportion

I'm at a bookstore with $\$35$ in my pocket and a $20\%$-off coupon. what is the cost of the most expensive book i can buy with my money and the coupon? (assume that there are books of every possible price in the bookstore. it's a large bookstore! )