Can someone multiply the numerators and denominators for me, every time i do it i mess up or get confused

Eileen purchased 3.4 pounds of apples at the total cost of $19.72. if she purchases 6.2 pounds of apples at this store, how much would it cost?

Need solving this second acceleration problem.

If it 8 inch candle burns at 7/10 inch per hour and a 6 inch candle burns at 1/5 inch per hour after how many hours would both candles be the same height