Jane and Fred each have their own collection of red and blue bingo chips. The ratio of the number of Jane’s chips to the number of Fred’s chips is 3:2. When they combine their chips, the ratio of the number of red chips to the number of blue chips is 7:3. For Jane’s chips, the ratio of the number of red chips to the number of blue chips is 4:1.

What is the ratio of the number of red chips to the number of blue chips for Fred’s bingo chips?