PEMDAS
parenthesis, exponents, mult/division, add/subtract
parenthesis: 4+0.2= 4.2
exponents: 10^2= 10×10= 100
new equation: 10-5/100×0.4(4.2)
multiply/divide: 10-(1/20)×.4×4.2
10-(0.05)(0.4)(4.2)
10-0.002×4.2
add/subtract: 10-0.0084 = 9.9916
~this feels like a wrong answer~