Verified answer

Bonsoir

2/5 x 5/4 x 4/7

= 5/5 x 4/4 x 2/7

= 1 x 1 x 2/7

= 2/7

1/(3/5) + (3/5)/2

= 5/3 + 3/(5 x 2)

= 5/3 + 3/10

= (5 x 10)/(3 x 10) + (3 x 3)/(10 x 3)

= 50/30 + 9/30

= 59/30

(16^3 x 25^4) / (2^10 x 5^7)

= [(4^2)^3 x (5^2)^4]/[2^10 x 5^7]

= [((2^2)^2)^3 x 5^(2x4)]/(2^10 x 5^7)

= (2^(2x2x3) x 5^8)/(2^10 x 5^7)

= (2^12 x 5^8)/(2^10 x 5^7)

= 2^(12-10) x 5^(8-7)

= 2^2 x 5

= 4 x 5

= 20