I actually created my own trick to find the answer to these problems. (Only works if both numbers are double digits, and if it is a "# is what percent of #" equation
Change the first number (28) by placing a decimal in the middle
2.8
Then divide 2.8 by 40
2.8 ÷ 40 = 0.07
Now multiply by 1000
0.07 x 1000 = 70
70% is your answer
