number of lunchers ---- x
number of non-lunchers --- 30-x
5x + 3(30-x) = 110
5x + 90 - 3x = 110
2x = 20
x = 10
10 took their own lunch, 20 bought their lunch
check:
10(5) + 20(3) = 110
30 children are going on a trip. It costs £5 including lunch. Some children take their own packed lunch. They pay only £3. The 30 children pay a total of £110
How many children are taking their own packed lunch?
2 answers
x = included, y = bring own
y = 30 - x
5x + 3y = 110
Substitute 30-x for y in second equation and solve for x. Insert that value into the first equation and solve for y. Check by inserting both values into the second equation.
y = 30 - x
5x + 3y = 110
Substitute 30-x for y in second equation and solve for x. Insert that value into the first equation and solve for y. Check by inserting both values into the second equation.
1 answer