```{r, include = FALSE}
## Generate two random fractions based on numbers from 1 to 10
f1 <- sample(1:10, 2, replace = FALSE)
f2 <- sample(1:10, 2, replace = FALSE)
a <- f1[1] 
b <- f1[2] 
c <- f2[1] 
d <- f2[2]

## Save random fractions a/b and c/d as character
## (don't forget escaping \\ within the math mode)
fr1 <- paste0("$\\frac{", a, "}{", b, "}$")
fr2 <- paste0("$\\frac{", c, "}{", d, "}$")

## Possible answers
answers <- c(
  paste(fr1, "is greater than", fr2),
  paste(fr2, "is greater than", fr1),
  "Both fractions are equal"
)

## Correct solution
sol <- c(0, 0, 0)
if(a/b > c/d) {
  sol[1] <- 1
} else if(c/d > a/b) {
  sol[2] <- 1
} else {
  sol[3] <- 1
}

## Explanation
k <- answers[as.logical(sol)]
eq <- c(" > ", " < ", " = ")[as.logical(sol)]
explanation <- paste0(k, " since $", a, " \\cdot ", d, eq, b, " \\cdot ", c, "$.")
```

Question
========
Which of these numbers is greater: `r fr1` or `r fr2`?

```{r, echo = FALSE, results = "asis"}
answerlist(answers, markup = "markdown")
```

Solution
========
`r explanation`

Meta-information
================
extype: schoice
exsolution: `r paste(sol, collapse = "")`