Question

efectctueaza stafeta calculelor si afla nr necunoscut a aceasta indica nr de copii din clasa a-iv care au călătorit cu trenul

Answer 1

ax15x3x10:50:9=25  (se aplica metoda mersului invers)
ax15x3x10:50=25x9=225
ax15x3x10=225x50=11250
ax15x3=11250:10=1125
ax15=1125:3
ax15=375
a=375:15
a=25

Answer 2

$a * 15 * 3 * 10 : 50 : 9 = 25 = \ \textgreater \ a * 15 * 3 * 10 : 50 = 25 * 9 = \ \textgreater \ a * 15 * 3 * 10 : 50 = 225 = \ \textgreater \ a * 15 * 3 * 10 = 225 * 50 =\ \textgreater \ a * 15 * 3 * 10 = 11250 = \ \textgreater \ a * 15 * 3 = 11250 : 10 = \ \textgreater \ a * 15 * 3 = 1125 = \ \textgreater \ a * 15 = 1125 : 3 = \ \textgreater \ a * 15 = 375 = \ \textgreater \ a = 375 : 15 = \ \textgreater \ \boxed{a = 25}$ $Black.Book$