18. 0.796 + 13 = 13.796 (the 13 is a whole number, so just put it in front of the decimal)
19. 15.63 + 24.36 = 39.99 (1+2=3 ; 5+4=9 ; 6+3=9 ; 3+6=9)
20. 19.86 - 4.94 = 14.92
21. 82 - 67.18 = 15.18 (again, whole number, there's no decimals to subtract, so leave them be)
22. 14.39 - 12.16 = 2.23 (1-1=0 ; 4-2=2 ; 3-1=2 ; 9-6=3)
My estimated answer for 1 is x=1.59 or x=-1.26 and my exact answer is (in word form) x= 1 plus or minus the square root of 73 over 6. my estimated answer for 2 is x=-0.34 or x=1.74 and my exact answer (in word form) is x= -7 plus or minus the square root of 109 over -10. I took a picture of my work and hopefully you can read it
' 40% ' means 0.4 .
You said that 60 = 0.4 x Full
Divide each side by 0.4 : 60 / 0.4 = 1 x Full
Full = 150 .