Please help me sort out these. I don't understand linear equations.

Find the missing dimension! need asap! tiny square is a =3025 in ²

y=2x−1 5x−4y=1 is (1,1)(1,1) a solution of the system?

Identify the percent of change as an increase or a decrease. 75 people to 25 people response - correct increase decrease question 2 find the percent of change. round to the nearest tenth of a percent.