Question

4 students spent 12$ on a school lunch.At this rate,find the amount 10 students would spend on the same school lunch..

Answer 1

4 students spend $12.
8 students would spend $24.
So, you need only two more students to buy lunch.
So HALF of what the 4 students pay, would mean 2 students pay $6. Or, each student pays $3.
So if 8 students spend $24. Add the $6 from the other two students, and the answer would be: 10 students spend $30.

To make it easier than that.
Find the price each student pays. So:
12/4= $3
Multiply $3 by the number of students.
$3 x 10 = $30

Answer 2

4students=12 dollars

Find the value each student spends
1student=12/4 dollars
1student=3 dollars

multiply both sides by 10 to get

10students=3*10 dollars

10students=30 dollars

10 students would spend 30 dollars