Answer:
Noor's age is 12 & Salma's age is 18
Step-by-step explanation:
Noor's age: N
Salma's age: S
[tex]N+S=30[/tex] : given
[tex]N - 3 = \frac{S}{2}[/tex] : given
[tex]N = \frac{S}{2}+3[/tex] : isolate "N"
[tex]\frac{S}{2}+3 + S = 30[/tex] : substitute the value of N for N to find the value of "S"
[tex]\frac{S}{2} + S = 27[/tex] : subtract 3 from both sides
[tex]\frac{S}{2}*2 + S*2 = 27*2[/tex] ≡ [tex]S + 2S = 54[/tex] : multiply both sides by 2
[tex]3S = 54[/tex] : add like values
[tex]\frac{3S}{3} = \frac{54}{3}[/tex] : divide both sides by 3
S = 18
now insert that value into the initial equation:
[tex]N + 18 = 30[/tex]
[tex]N = 12[/tex] : subtract 18 from both sides
