Simple if then Statement

The last brace } lacks an opening brace is the immediate cause. See the FAQ: How to do a minimal reproducible example reprex for beginners for future reference.

There are also easier ways to do operations based on logical tests

suppressPackageStartupMessages({
  library(dplyr)
})

mtcars %>% filter(mpg > 20 & cyl == 4 & hp > 100)
#>               mpg cyl  disp  hp drat    wt qsec vs am gear carb
#> Lotus Europa 30.4   4  95.1 113 3.77 1.513 16.9  1  1    5    2
#> Volvo 142E   21.4   4 121.0 109 4.11 2.780 18.6  1  1    4    2

Created on 2021-02-20 by the reprex package (v1.0.0)