Need help this is new to me

Which elements in the set below are integers? 12, –3⁄4,√ 25 , –7, √ 5 , 14⁄7, 9 a. 12, √ 25 , –7, 9 b. 12, √ 25 , –7, 14⁄7, 9 c. –3⁄4, 25 , √ 5 ,14⁄7 d. 12, –7, 9

Me because some of question i don’t understand

The value of x in this system of equations is 1. 3x + y = 9 y = –4x + 10 substitute the value of y in the first equation: combine like terms: apply the subtraction property of equality: apply the division property of equality: 3x + (–4x + 10) = 9 –x + 10 = 9 –x = –1 x = 1 what is the value of y?