((This is not for a graded class assignment or exam, just assigned by my boss to become familiar with MLRs))

I have a variable Y (length 99) and 10 variables X1-X10 to build a regression model.

Basic correlations with each variable and the dependent output Y show no correlations stronger than .15 and within 'independent' variables no stronger than .22.

While my boss claims that an R^2 value greater than .85 is possible and has been done before with this dataset, I am not sure how to achieve a linear regression equation that approaches anything close to this. - attempts have only achieved R^2=.54 and adjusted R^2 of .49

If anyone can help me or recommend a site that is not https://www.statmethods.net/stats/regression.html or http://r-statistics.co/Linear-Regression.html that would give a good procedure for doing something like this I would appreciate it!!