Răspuns :
(r-7):6×9+9×5=90
(r-7):6×9+45=90
(r-7):6×9=90-45
(r-7):6×9=45
(r-7):6=45:9
(r-7):6=5
r-7=5×6
r-7=30
r=30+7
r=37
(r-7):6×9+45=90
(r-7):6×9=90-45
(r-7):6×9=45
(r-7):6=45:9
(r-7):6=5
r-7=5×6
r-7=30
r=30+7
r=37