Tolongin ya,thankyouu

4) 2^-3-(-7) = 2^4 = 16

5) √80 - √20 + √45 = √16x5 - √4x5 +√9x5
= 4√5 - 2√5 + 3√5 = 5√5

6) √90 : √5 = √90:5 = √18 = √9x2 = 3√2