The question is incomplete without the absorbance vs. concentration curve for copper sulfate (CuSO₄). Nonetheless, enough information will be provided to help you answer the question correctly.
Generally, in such questions, the relationship between the absorbance measured at a particular wavelength (510 nm in the current case) and the concentration of the desired species (CuSO₄ in this case) is provided. A curve is plotted with absorbance as its y-axis and concentration as its x-axis. The relationship between the absorbance and concentration is determined by finding the equation of the line in slope-intercept form (y = mx + b, where m is the slope of the line and b is the intercept). For any other value of absorbance, the value is simply substituted into this equation, and the corresponding concentration is determined.
For example, let's say the relationship in the given case is
y = 2.5 x + 0.5
(This equation is only for illustration purposes—kindly use the equation given in your own data.)
And let's say that absorbance, y, is equal to 1.1 units.
Then x can be calculated:
1.1 = 2.5 x + 0.5
or, 1.1 - 0.5 = 2.5 x
or, x = 0.24 M
So, use the equation given in your own data, and, using this illustration, calculate the value of CuSO₄ concentration.
Hope this helps.