The question and picture don't match up. You basically just have to plug and play numbers. Since the first jar has 7 more than the second and the third jar has 3 less than then second, this answer works perfectly: first:19 second:12 third:9 19+12=31 31+9=40
However, if you base it on the jars, none of the answers are correct and the verbal expressions aren't accurate. There are 16 bugs in the first jar, 6 in the second, and 3 in the third. That does NOT equal 40, it equals 25. If you take 25 from 40, that leaves 15 left not accounted 4, which would logically require giving them amount to equal the 40 while following the verbal expressions. This adds 4 to third for 19, 6 to second for 12, and 6 to first for 9, which is 6+6=12+3=15
In other words, there are multiple ways to do it, but plugging in numbers is the easiest way, once you know the final result, but only after making the expressions stated by the verbal expressions..
How old or dumb are you that you never learned algebra or systems of equations? ---