Answer:
C=30
Step-by-step explanation:
Supposing that we have the lines
x+2=10y
and
3x+6=Yc.
Note that dividing by 3 the second line can be rewritten as
x + 2= Y c/3.
Remember that a line is written as 
, in our case, both lines have 
and 
. Therefore, in orther that the two lines are equal, we need that 
, hence 
2040 = n/2(20+(n-1)4)
4080 = n(20+4n-4)
4080= 20n +4n^2 -4n
1020 = 4n + n^2
n^2 +4n -1020 =0
use common formula (can't write out so just look at answers. sorry)
which gives answers of n=-34 and n=30. since n can only be positive, n=30 so there are 30 rows. I liked that challenge
Evaluate: 2(1/4) + 2/5 ÷ (-1/2) - 1/4
⇛9/4 + 2/5 ÷ (-1/2) - 1/4
Take the LCM of the 4 and 5 is 20.
Again, 2 and 4 is 4.
⇛[(54+8)/20] ÷ [(-2 - 1)/4]
⇛62/20 ÷ (-3/4)
⇛62/20 × 4/-3
⇛62/{5*(-3)}
⇛62/-15.
