it would be 70/100 then it would go down to 7/10 so 1/10 of 70kg would be 7kg because you change 70 you make it a decimal witch is .70 or .7 now make that into a fraction and it would be 70/100 or 7/10 then you take your 7 because its 1/10 of 70. Or you could do it a whole lot easier way and just divide 70 by 10 and get 7. There you have it your answer is 7.
By substitution. Get y or x alone then insert it into the other equation solving for one of the two variables. After that substitute ur answer into one of the equations then solve.
