Answer:
35 dogs
Step-by-step explanation:
x ---> the number of dogs
y ---> the number of cats
The last week of January we have 20 cats and the ratio is the same
so
\frac{x}{y}=\frac{49}{28} ----> equation A
y=20 ---> equation B
substitute equation B in equation A
\frac{x}{20}=\frac{49}{28}
solve for x
x=\frac{49}{28}(20)=35 dogs
check the picture below.
if we run a vertical line test on that graph, like you see there, namely run vertical lines through it, we can see that one vertical line only hits the graph once, not twice or more.
on the vertical line test, if the graph is hit only once by each of the vertical lines, then the graph is a function.