m=mama
f1=fiul cel mare
f2=fiul cel mic
m+f1+f2=45 (acum 5 ani)-> acum
m+5+f1+5+f2+5=45+5+5+5
f1=2×f2
m+2×f2+f2+15=45/-15
m+3×f2=30
m=f1+f2 (peste 18 ani)
m-18=f2×3-18×2
m-18=f2×3-36 /+18
m=f2×3-18
f2×3-18+3×f2=30
6×f2-18=30 /+18
6×f2=48 /÷6
f2=8 -> f1=2×8=16->
m=f1+f2+18
m=8+16+18
m=24+18
m= 42