Math topic中文Age problemsUse the invariant age difference to convert age questions into sum-difference-multiple problems.Learn these firstSum-difference-multiple problemsPractice questions1母亲26岁结婚，第二年生了儿子，若干年后，母亲的年龄是儿子的3倍．此时母亲的年龄为（ ） A. 39岁 B. 42岁 C. 45岁 D. 48岁2Anna and Bella are celebrating their birthdays together. Five years ago, when Bella turned 6 years old, she received a n…