Explanation:
4. 3x+7=37, 3x=37-7=30 x=30÷3=10
5. 31=7x-11, 7x=31+11=42 x=42÷7=6
6. 11k-84=92, 11k=92+84=176 k=176÷11=16
7. 4r+13=57, 4r=57-13=44 r=44÷4=11
8. z÷4+16=21, z÷4=21-16=5 z=5×4=20
9. 7=t÷6-3, t÷6=7+3=10 t=10×6=60
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