Question 979104
I can say:
{{{ d/f = 37/39 }}}
{{{ d + f = 152 }}}
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{{{ d = (37/39)*f }}}
by substitution:
{{{ (37/39)*f + f = 152 }}}
{{{ 37f + 39f = 152*39 }}}
{{{ 76f = 5928 }}}
{{{ f = 78 }}}
I get 78 frogs in the pond