SOLUTION: Hi math is not my best subject. My son has a math problem that got me stuck. He is in 2nd grade and their doing Problem Solving Algebra. The problem is 10+50=80- ___=

Algebra ->  Numeric Fractions Calculators, Lesson and Practice -> SOLUTION: Hi math is not my best subject. My son has a math problem that got me stuck. He is in 2nd grade and their doing Problem Solving Algebra. The problem is 10+50=80- ___=       Log On


   

Question 391147: Hi math is not my best subject. My son has a math problem that got me stuck. He is in 2nd grade and their doing Problem Solving Algebra.
The problem is
10+50=80- ___=
20+30=90- ___=
Im a little confused on how to get these answer and explaining to a 7year old.
THanks for your help in advance.
Answer by richard1234(7193) About Me  (Show Source):
You can put this solution on YOUR website!
Let the blank number be x. Add 10+50 to get 60, so we have

60 = 80 - x. Add x to both sides to get 60 + x = 80, subtract 60 to get x = 20. The second problem is very similar to the first one.

In terms of explaining to a 7-year old...I had a math tutor from a university who, even on the most difficult olympiad problems, would replace some expression like ln+%28x%5E3+%2B+e%5Ey%29 with an apple or pear, and do the problem in terms of apple. It worked quite well for me. You might want to try that with your son. This is similar to an elementary algebra problem, but might be more visual and appealing than using "x."