you never specify the aim of your equation.. but the one who gave the answer first was partly right, but why 30? its 3 to be exact..the thing there that is only lacking is that, the exact explanation to get you fully understand the equation... the equation aims you to get the x as a variable... to get x , u need to transpose from the equal sign either way the 162 to the next side and that would become be -162, and add the same constant (-18) to the -162 and that would become be 0 = 53x +7x - 180...add up the same term with the same exponent of a variable x, 53x + 7x and that would equal to 60x.. 0 = 60x - 180 ...transpose back the -180 to the other side and become to 180 = 60x ...divide 60 to cancel out the coeficient of x from the other side , 180/60 = x , thus the value of x = 3 ...
simpler solution: transpose the -18 to the other side: 162 + 18 = 53x + 7x : --> 180 = 60x and so the rest ......
note: to get the variable x, just aim to meet the same term and add/subtract whatever may it come and divide.
hope this can help...