Question

1) calculati prodsul numerelor intregi -2 si -15
2) se considera proportia 7/a=b/8 calculati a ori b
3) daca din 15 m de stofa se confectioneaza sase costume, aflati cate costume se confectioneaza din 25m de stofa

Answer 1

1) -2×(-15)=+30
2) 7/a=b/8 => notam cu k
a=k/7 iar b=8k
a×b= k/7 × 8k
a×b=k/7×8k/1
a×b=8k la a 2a/7(mai mult nu pot afla)
3)vom folosi regula de trei simpla
15m.............6buc
25m............. X buc
15/25=6/X
3/5=6/x
3×X=5×6
3x=30
x=10 costume