Math reasoning please help and please show work

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

Asix-sided die of unknown bias is rolled 20 times, and the number 3 comes up 6 times. in the next three rounds (the die is rolled 20 times in each round), the number 3 comes up 6 times, 5 times, and 7 times. the experimental probability of rolling a 3 is 10 %, which is approximately % more than its theoretical probability. (round off your answers to the nearest integer.)

What is 2/4+1/4,find the common denominator