WAEC - Mathematics (2023 - No. 7)
One-third of the sum of two numbers is 12, twice their difference is 12. Find the numbers.
22 and 14
20 and 16
21 and 15
23 and 13
Vysvětlení
Let the two numbers be x and y
\(\frac{1}{3}( x + y) = 12\)
then x + y = 36 ..........i
2( x - y) = 12
x - y = 6 ............ii
add equations i and ii
2x = 42
x = 21, put x = 21 into equation i
x + y = 36
21 + y = 36
y = 36 - 21 = 15
therefore the numbers are 21 and 15