(38+b)*12=840

38+b=840:12

38+b=70

b=70-38

b=32

14(p-30)=630

14p-420=630

14p=630+420

14p=1050

p=1050:14

p=75

(43-c)*17=289

43-c=289:17

43-c=17

c=43-17

c=26