123 is a linear pair with the inside angle so
180-124= 57. Now we have two inside angles and a triangle has to be 180 degrees so
57+42=99 we know that both angles equals 99 so
180-99=80. The third angle is 81 and is a linear pair with x soooo
180-81=99
X is equal to 99. You can also do corresponding angles and have X be 99 because of the inside angle that’s also 99
Let's say the savings in your account are given by $V, the number of weeks by n and the starting balance by $x:
V = x + 200n
Now if after saving for 4 weeks you have $1700 in your account, then:
1700 = x + 200*4
1700 = x + 800
x = 900, thus your starting balance is $900
Using this information we can now write up the general equation for the savings at the end of each week:
V = 900 + 200n
