i really dont understand this i feel like im goin around in circles....if u can help i owuld love that!!!

2/3(2c+5)=8 how do u do this?

also x/4 -15=10 would x b 100 or did i do that wrong?

an i think i did this one right too but im not sure....

7(2x-5)=28+5x....would this b -7/9?im not sure how i got that though