2又四分之一*3又二分之一+7.75/七分之二
= 9/4 * 7/2 + 7.75 /(2/7)
= 9/4 * 7/2 + 7.75* 7/2
= 7/2*(2.25 + 7.75)
= 7 / 2 * 10
= 7 * 5
= 35