Bonjour,
Soit P=pull et T=teeshirt
7P+12T=187
9P+15T=237
9P+15T=237 36P+60T=948
7P+12T=187 35P+60T=935
(36P+60T)-(35P+60T)=948-935
36p+60t-35p-60t=13
P=13
le pull coute 13€
si le pull coute 13€
alors
7P+12T=187
7(13)+12T=187
91+12T= 187
12T=187-91
12T=96
T=8
le tee shirt coute 8€