the given equation is
a - 15 = 35
a = 35 + 15
a = 50
as you know when we move the number across the equal sign it changes its sign
only when the numbers are in addition or in subtraction.
the second equation is
r + 9 = 158
r = 158 - 9
r = 149
if a number is n times a then if we put it across the equal sign then it will be in division of the other side number
for examples
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