I would say he can because 1+1 = 2
3a+7+2a and 7a+5. These expressions are not equivalent. 5a+7 does not equal 7a+5.
4367 ÷ 0.004 is 1091750. To solve this, you can use long division, by setting up the equation. Make sure to move the decimal. Then, divide the first digit, then the first two digits, and so on.
7 5/12 or 7.41
17 1/21 or 17.04