Answer:
Samuel is 18
Yvonne is 22
Explanation:
So let y represent yvonne and s as samuel
Let's set-up two equations
y + s = 40
y + 4 = s
So since s = y + 4 lets substitute
y + (y + 4) = 40 which gives us;
y + y + 4 = 40
Collect like terms;
2y + 4 = 40
Subtract 4 from both sides
2y = 36
Divide both sides by 2
y = 18
y + 4 = 18 + 4 = 22
So yvonne is 22 years of age
40 - 22 = 18
So Samuel is 18 years of age