Answer:
The smallest number is 7
Explanation:
Using simultaneous equation;
x+y = 18.....(1)
4x-y = 17.....(2)
from equation (1)..
x+y = 18
y = 18-x...(3)
substitute y into equation (2)
4x-y = 17
4x-(18-x) = 17
4x-18+x = 17
4x+x = 17+18
5x = 35
x = 35÷5
x = 7
substitute x into equation (3)
y = 18-x
y = 18-7
y = 11
Therefore; x=7
y=11
11+7=18
(4×7)-11=17
the smallest number is 7