a, `-6,5 + 14/25 . (-5)/7`
`= (-65)/10 + (-2)/5`
`= -65/10 + (-4)/10`
`= -69/10`
b,`(5^62 . 16^15)/(8^19 . 125^21)`
`= (5^62 . (2^4)^15)/((2^3)^19 . (5^3)^21)`
`= (5^62 . 2^60)/(2^57 . 5^63)`
`= 2^3/5`
`= 8/5`
c, `| -4/3 + 1 | - (-2/3)^21 : (-2/3)^19`
`= | -1/3 | - (-2/3)^2`
`= 1/3 - 4/9`
`= 3/9 - 4/9`
`= -1/9`