Step-by-step explanation:
(2c+c) + 12 =78
3c + 12 = 78
78 - 12 = 66
66 ÷ 3 = 22
22 + 22 + 22 + 12 = 78
{ C = 22 }
first and second part put 0.75, then multiply 0.75 by 2 to get 1.50, then write in the third part 1 and 1/2
hope this helps

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C adding a number to itself