Răspuns :
Mama- m
Fiica- f
M+f= 40 --> M= 40–f
M= 4•f
40–f= 4•f
40= 5•f --> f= 8 ani
M= 40–f= 40–8= 32 ani
M+x= 2•(f+x)
32+x= 2•(8+x)
32+x= 16+2x. /–x
32= 16+x. /–16
16= x
Peste 16 ani.
Fiica- f
M+f= 40 --> M= 40–f
M= 4•f
40–f= 4•f
40= 5•f --> f= 8 ani
M= 40–f= 40–8= 32 ani
M+x= 2•(f+x)
32+x= 2•(8+x)
32+x= 16+2x. /–x
32= 16+x. /–16
16= x
Peste 16 ani.