16x5=80 cause if it bounces 16 times 5 times then
The equation (1) is divided by 2 to create new equivalent system of equations.
Step-by-step explanation:
The given systems of equations are:

Considering 8y instead of 8 in eq(1)
We need to identify what action was completed to create this new equivalent system of equations? 
Comparing given equations we came to know that equation(1) is divided by 2 to get the new equation i.e

While second equation is same as given.
So, The equation (1) is divided by 2 to create new equivalent system of equations.
Keywords:System of Equation
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I cant really see the words
The greatest common factor is 6xy
Explecit formula
hmm, seems to be a geometric sequence
so
an=a1+d(n-1)
d=common differnce
a1=first term
given
a1=firstterm=9.2
and the difference between each tierm is 1.8
an=9.1-1.8(n-1) is da equation
so 4th option